Outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in the neonatal intensive care unit of a university hospital in Japan

Methicillin-resistant Staphylococcus aureus (MRSA), specifically sequence type 1 (ST1) with staphylococcal cassette chromosome mec (SCCmec) type IV and negative for Panton-Valentine leukocidin (PVL), is endemic in Japanese hospitals. This particular clone has been frequently reported in Japan. MRSA outbreaks are typically analyzed using methods such as SCCmec typing, pulsed-field gel electrophoresis (PFGE), and more recently, whole-genome sequencing (WGS), which has gained attention due to its high discriminatory power. Although PFGE and other conventional methods are widely used to track MRSA outbreaks, WGS has been increasingly employed in recent studies. In this project, we analyzed an MRSA outbreak at a university hospital in Japan using both conventional methods and WGS.